Biomedical subjects
A Hughes
Publications and source records attributed to A Hughes.
A useful table of reduced schematic eyes for vertebrates which includes computed longitudinal chromatic aberrations.
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The artefact of retinoscopy in the rat and rabbit eye has its origin at the retina/vitreous interface rather than in longitudinal chromatic aberration.
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A rose by any other name... on 'naming of neurones' by Rowe and Stone.
Rowe and Stone dispose of descriptive terminologies for retinal units as 'essentialist' and argue for a 'neutral' multifactorial system redefined from previous W, X. Y nomenclatures. It is argued here that descriptive terminology need not be either essentialist or undesirable and that the W, X, Y terminology is too confused with false associations to be satisfactory. The synthetic power of the W, X, Y nomenclature was lost with the discovery of concentric W cell receptive fields, the projection of the W cells to the LGN and the suggestion of overlap between X and W conduction velocity groups. It was made methodologically unsound by its employment for the naming of Nissl stained soma classes before the identity of individual somas with the physiological entities can be demonstrated. Although now redefined, the identity of symbols in the several vintages of the W, X, Y system leads to inevitable confusion. The current tripartite division of a multidimensional quality space without cluster analysis is not neutral because it emphasises conduction velocity but represses the diversity of W receptive fields. The concise, apt and memorable descriptive receptive field terminologies are more desirable in that they are operationally based and approximate the unit's transfer function--the parameter most significant to the central nervous system in its information processing task; thus they are more suited for cross species comparison because of a probably bountiful source of functional hypotheses. The lack of taxonomic neutrality in the W, X, Y system has recently been emphasised by its failure to adequately classify rabbit retinal receptive field categories.
Assessment techniques for deaf-blind children.
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An estimate of image quality in the rat eye.
The point spread function on the optic axis of the rat eye is indirectly estimated to increase from a half-height width no greater than 12.5' to not less than 36' after dilation of a 0.33 mm pupil diameter to 3.0 mm.
Severe megaloblastic anaemia caused by maloprim.
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The neural representation of visual space.
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Evidence for intestinal origin of transcobalamin II during vitamin B12 absorption.
The plasma binding of newly absorbed, radioactively labelled vitamin B12 was studied during a urinary excretion (Schilling) test. Vitamin B12, after being absorbed from the gut, enters blood attached to transcobalamin II, which seems to be derived from the ileal enterocyte. The absorbed B12 re-enters the blood stream after the transcobalamin II-B12 complex is cleared by the liver and it is then excreted into the urine during the Schilling test.
The refractive state of the rabbit eye: variation with eccentricity and correction for oblique astigmatism.
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Stability of ribosomes of Staphylococcus aureus S6 sublethally heated in different buffers.
Cells of Staphylococcus aureus heated at 52 degrees C in magnesium-chelating buffers [pH 7.2, 50 mM potassium phosphate or 50 mM tris(hydroxymethyl)-aminomethane containing 1 mM ethylenediaminetetraacetic acid] leaked 260-nm absorbing material, shown to be RNA, and suffered destruction of their ribosomes. These cells did not regain their salt tolerance when repair was carried out in the presence of actinomycin D (5 microgram/ml). Cells similarly heated in magnesium-conserving buffers [pH 7.2, 50 mM tris(hydroxymethyl)aminomethane containing 10 mM MgCl2 or piperazine buffer] did not leak RNA, suffered no ribosomal damage when heated for 15 min, and recovered, at least partially, in the presence of actinomycin D. Ribosomal damage, is therefore, a consequence of Mg2+ loss and is not an effect of heat per se. Cells suspended in either Mg2+-chelating or Mg2+-conserving buffers lost salt tolerance to about the same extent during heating at 52 degrees C. Therefore, sublethal heat injury can not be attributed to ribosomal damage.
Toward identifying effective agents in use of biofeedback to decelerate stuttering behavior.
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The pigmented-rat optic nerve: fibre count and fibre diameter spectrum.
A well distributed electron microscopic sample of 52,000 fibres from the pigmented rat optic nerve cross section indicates a total count of 120,000 +/- 1,600 (S.E.M.) fibres ranging from 0.437 mu to 5.2 mu in diameter. The fibre diameter spectrum is essentially unimodal with a peak at 1.0 mu with a well developed "tail." These results are identical to those available in the literature for the albino rat.
An evaluation of the agargel electrophoretic method for the analysis of specific steroid binding proteins.
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A proposal for assessment of hormone sensitivity and consequent endocrine therapy of breast cancer.
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The refractive state of the rat eye.
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Variations in uterine cytosolic oestrogen and progesterone receptor levels during the rat oestrous cycle.
The levels of cytosol receptors for both oestradiol and progesterone were simultaneous monitored in the uterus at various stages of the rat oestrous cycle. The use of the synthetic gestagen R-5020, with its high specificity and affinity for the progesterone receptor, eliminated interference arising from corticosteroid binding globulin (CBG) contamination of uterine extracts. The results show that the patterns for both receptors are markedly different over the cycle. The variation can be correlated with changes in ovarian steroid output. The results also suggest that oestradiol and progesterone interact not only with their specific receptor, but also influence the other receptor system.
The rabbit optic nerve: fibre diameter spectrum, fibre count, and comparison with a retinal ganglion cell count.
This electron microscopic study indicates that the rabbit optic nerve contains 394,000 +/- 20,000 (p less than 0.05) nerve fibers, of which at least 98% are myelinated. The fibre diameter spectrum of the nerve is unimodal and ranges from 0.25-7 mum with its peak at 0.75 mum. The projection of the visual streak fibres is not apparent in local diameter spectra near the optic nerve head. Integration of a ganglion cell density map of the retina from another rabbit indicates a total ganglion cell count lying between 455,000 and 547,000. The optic nerve fibre and ganglion cell counts are both substantially greater than the maximum fibre count previously reported.